alexo-, alex-, alexi-

(Greek: defend, protect, ward off, keep off)

A preservative against evil; a safeguard against bad: The hunter wore an alexikakon around his neck as a talisman to protect him from wild animal attacks.

alexidine

An antibacterial substance.

alexin

1. A defensive substance in normal serum that destroys bacteria and other cells.
2. A name for a class of substances found in blood-serum, having the capacity of destroying bacteria, etc., and thus guarding against infection.

alexipharmac

1. Warding off the ill effects of a poison.
2. An antidote or remedy for poisoning.

alexipharmac

alexipharmacal

alexipharmic, alexipharmac

1. Antidotal; an antidote.
2. Expelling or counteracting poison.
3. An antidote against poison or infection; a counterpoison.
4. A remedy or preservative against poison; an antidote.

alexipyretic

A substance that reduces fever; antipyretic.

Alexis

alexiteric

alexitery

alexocyte

phytoalexin

Any substance that is produced by plant tissues in response to contact with a parasite and specifically inhibits the growth of that parasite.

The term was originally defined with regard to fungal parasites only, but in 1956 it was extended to cover all parasites [According to the Oxford English Dictionary].